I organized and led a team of three to
design this forklift that broke all previous competition records to
place second in the BYU Mechatronics Competition 1999. My team,
comprised of only mechanical engineers, finished second out of nine
other multidisciplinary teams. Even though this was my teams first
time programming a microcontroller and designing a mechatronic system,
we were able to finish ahead of almost all other more experienced teams.

Click Image forLarger View

The competition was simple.
Autonomously navigate a miniature factor floor, scanning and delivering
packages to their proper locations. Do this the fastest with the
fewest mistakes and you win. In order to accomplish this a
forklift must be able to:

Follow the white line on the factory floor while navigating
all turns, pickup and drop-off locations

Use a barcode scanner to properly identify packages

Pickup and drop off packages at varying heights

Sense when a package is properly positioned on the forks

Receive an infrared signal from the factory IR tower that
tells the forklift to move clockwise or counterclockwise around
the circle at the center of the factory floor

Video of Forklift

Click
here
or on the icon to the right to download and play a video of the forklift
in action. This file is 5.9 MB in size so please be patient.

The video begins with the forklift
calibration. This consists of driving the forklift over the white
line on the factory floor. The forklift is then positioned at
the starting line and set in motion. It scans a package,
identifies the contents and delivers it. It then moves to the next
package, identifies the contents and delivers it to the proper location.
The forklift returns to the center of the factory floor, picks-up and
identifies the contents of the next package and then waits for
information from the factory IR tower to know if it should travel
clockwise or counterclockwise around the circle. The package is
then delivered and the forklift returns to the starting line.

Detail Pictures of the Forklift

Click any of the thumbnails
below for a larger view of the image.

Line sensor array used white LEDs and photo
resistors purchased at our local Radio Shack to read the line on the
factory floor. The microcontroller (The
Handy Board) was programmed to use PID control to follow the line.

The gear train consisted of two DC gear
motors wired directly to the microcontroller.

Rear swivel wheel that made it possible to
steer the forklift by controlling the speed of each drive wheel
independently.

The barcode scanner used to scan and
identify packages on the factory floor.

The hall effect sensor used to detect if a
package was positioned properly on the forks.

The drive motor (DC geared) and sensor
(single turn potentiometer) used to move the forks and keep track of
their position.

The infrared sensor positioned at the top of
the fork lift tower. The upper pulley of the forklift drive belt
can also be seen here. The belt and pulley were taken from an old
dot matrix printer.

The entire fork lifting mechanism.

This mechanism, using a standard hobby servo
and a custom servo horn, was used to lock our rear swiveling wheel in
place so that the forklift would backup in straight line. This
ingenious mechanism saved several hundred lines of code that would have
been otherwise necessary for backing up in a straight line.